Kidneys Flashcards
Each nephron contains a filter known as the …
glomerulus
The kidneys sit on the … wall of the abdomen, outside the … cavity
posterior
peritoneal
The … cappilary network joins the interlobular vein
peritibular
List the four vascular components of the nephrons
1 - Afferent arteriole
2 - Glomerulus (capillaries)
3 - Efferent arteriole
4 - Peritubular capillaries or vasa recta
Where within the nephron does filtration take place?
The glomerulus
T or F
Any substance that ends up in the kidney tubule will get excreted
T
T or F
The renal pelvis connects to the renal vein
F
It is connected to the ureter
… to …% of cardiac output goes to the kidney
20 to 25
The standard, healthy glomerular filtration rate is …ml/min
125
…% of plasma flowing through the kidney is filtered
20
…% of kidney filtrate is reabsorbed by the body
99
Why can creatinine or inulin be used to estimate GFR?
Because they get filtered but not reabsorbed or secreted
Define renal clearance
The volume of plasma the kidneys can clear of a particular substance in a given time.
What eGFR values indicate stage 1 kidney disease?
90+
What eGFR values indicate stage 2 kidney disease?
89-60
What eGFR values indicate stage 3 kidney disease?
59-45
44-30
What eGFR values indicate stage 4 kidney disease?
29-15
What eGFR values indicate stage 5 kidney disease?
Less than 15
Why do patients with kidney disease develop anemia?
Kidneys produce erythropoietin (EPO) a hormone that stimulates bone marrow to produce red blood cells. Diseased or damaged kidneys do not produce sufficient EPO which causes less blood cells to be produced, causing anemia.
What are the 4 main functions of the kidney?
– Regulation of water & electrolyte volume & osmolarity
– Regulation of acid-base balance
– Excretion of metabolic waste products and foreign chemicals
– Secretion of enzymes
Name all the blood vessels associated with the nephron
- Afferent arteriole
- Glomerulus (capillaries)
- Efferent arteriole
- Peritubular capillaries or vasa recta
List the arteries blood flows through to get from the aorta to the afferent arteriole in the kidney
- Renal artery
- Segmental artery
- Interlobular artery
- Arcuate artery
- Cortical radiate artery
List the veins blood flows through to get from the peritubular capillaries/vasa recta to the renal inferior vena cava
Cortical radiate vein
Arcuate vein
Interlobular vein
Renal vein
The kidney is made of individual functional
units called …
“nephrons”
The nephron is made up of what two components?
- Vascular components (blood vessels)
- A complex set of renal tubules
Put simply what is the purpose of the renal tubules in the nephrons?
carries the fluid filtered by glomeruli
termed the tubular filtrate
T or F
The interlobular artery and cortical radiate artery are interchangeable names for the same artery
T
The … arteriole supplies blood to the glomerulus
afferent
The ball of capillaries where filtration takes place is called the …
glomerulus
The … arteriole Carries blood away from the glomerulus
efferent
… capillaries are wrapped around the renal tubules
Peritubular
What are the peritubular capillaries important for?
important in
exchanging fluid inside the tubules into
capillaries and vice versa
T or F
The renal artery which carries blood into the kidney divides into
smaller and smaller blood vessels until it gives rise to the afferent arteriole.
T
The … is the filtration
unit of the kidney
Glomerulus
Before passing through the ureter to the bladder urine collects in the …
calyces
Match the tubular elements of the nephron to their function:
A. Bowman’s capsule
B. Proximal Tubule
C. Loop of Henle
D. Distal tubule/collecting duct
E. Renal pelvis
- Where the majority of reabsorption takes place
- Collects urine and funnels to ureter/bladder
- Controlled reabsorption (esp Na+ and H2O)
and secretion (K+ and H+) - Surrounds the glomerulus; collects filtrate
- Important for producing urine of varying
concentrations
A4, B1, C5, D3 and E2
What does glomeruler filtration rate measure?
the volume of plasma filtered per minute
T or F
eGFR increases in kidney disease
F
decreases
What is filtration fraction?
The fraction of
the renal plasma flow that is filtered in the
glomerulus during a single pass through
the kidney = GFR/Renal Plasma flow
…% of the filtrate is taken back into
the body
99
T or F
Glomerular filtration rate (ml/min) can be estimated using a molecule which gets reabsorbed but
does not get filtered or secreted.
F
Glomerular filtration rate (ml/min) can be estimated using a molecule which gets filtered but
does not get reabsorbed or secreted.
How do you calculate creatinine clearance?
Urine concentration of Cr/ Plasma concentration of Cr x urine flow rate
What is renal clearance?
volume of plasma kidneys
can clear of a particular substance in a given
time
How do you calculate renal clearance?
renal clearance rate (ml/min) = (concentration (mg/ml) of substance in urine x flow rate of urine formation (ml/min)) / concentration of same substance in plasma
What does it mean if renal clearance is 0?
substance was completely
reabsorbed, or not filtered
What does it mean if renal clearance is less than 125ml/min?
means substance
reabsorbed
What does it mean if renal clearance is greater than 125ml/min?
substance was secreted
(most drug metabolites)
What does it mean if renal clearance is equal to 125ml/min?
no net reabsorption or
secretion
T or F
GFR cannot be measured directly
T
Erythropoietin also known as … or …, is a glycoprotein cytokine secreted by
the kidney in response to ….; it
stimulates red blood cell production
(erythropoiesis) in the ….
haematopoietin or
haemopoietin
ellular hypoxia
bone marrow
What is glomerular filtration?
the movement of fluid and
solutes from the glomerular
capillaries into Bowman’s space.
What is tubular reabsorption?
the movement of materials from the filtrate in the tubules into the peritubular capillaries. (moving fluid back into the body)
What is tubular secretion?
the movement of solutes from the peritubular capillaries into the tubules
– Removing fluid from the body
T or F
some substances almost completely reabsorbed by the kidneys
T
T or F
Waste products highly reabsorbed from the kidneys
F
Waste products poorly reabsorbed
T or F
Ions are highly reabsorbed by the kidney
T
without tubular reabsorption → whole plasma volume &
essential solutes excreted within …min
30
For most substances that are actively reabsorbed (or secreted) there is a limit to the rate the solute can be transported, why is this?
Due to saturation of available carrier proteins (what is not transported will be excreted)
In a healthy individual what is the reabsorbance rate for glucose?
100%
In a healthy individual what is the reabsorbance rate for water?
99%
In a healthy individual what is the reabsorbance rate for sodium?
99.5%
In a healthy individual what is the reabsorbance rate for urea?
44%
T or F
The descending Loop of Henle undergoes osmosis whereas the ascending loop of henle is impermeable
T
Where in the nephron does the majority of water reabsorption take place?
In the proximal tubules (67%) via osmosis
Why can the presence or the absence of vasopressin influence the osmolarity of urine?
Vasopressin (another name antidiuretic hormone (ADH)) increases the tubular permeability in the collecting duct.
In which 3 parts of the nephron is water reabsorbed?
Proximal tubules
Loop of Henle
Distal tubule and collecting duct
Describe the pathway by which ADH secretion is lowered upon drinking
a litre of soft drink and water excretion raised?
Drinking a litre of soft drink lowers ECF osmolarity, lowers ADH secretion, lowers collecting duct permeability to H2O, lowers H2O reabsorption which increases H2O secretion
T or F
Dehydration will have no effect on plasma volume
F
It will reduce plasma volume
What is the kidneys response to dehydration?
- Retain sodium and water to minimise ECF osmolarity and volume loss (increasing ECF osmolarity)
- Osmoreceptors trigger thirst
- Increased ADH from the posterior pituitary
- Increased water reabsorption
- Decreased water excretion
Which parts of the nephron are under fine control from ADH?
Distal tubule
& Collecting Duct
Once released from the … pituitary vasopressin reaches the kidney via ….
posterior
systemic circulation
What effect does ADH have on the proximal tubule and collecting duct of the nephron?
increasing water reabsorption and thereby minimising loss of
water.
Via what mode of transport does the ascending loop of henle reabsorb sodium?
active transport
T or F
The descending loop of henle cannot reabsorb sodium
T
Where in the nephron in 64% of sodium reabsorbed?
The proximal tubules
The distal tubule and collecting ducts of the nephron reabsorb sodium under the fine control of…
aldosterone
T or F
Atrial natriuretic peptide is a protein
F
hormone
T or F
Atrial natriuretic peptide is a potent vasoconstrictor
F
vasodilator
Atrial natriuretic peptide regulates … and …
Regulates sodium balance and blood volume
Atrial natriuretic peptide acts on tubules to inhibit … reabsorption
sodium
T or F
Atrial natriuretic peptide can increase GFR
T
and thus further contributes to
increased sodium excretion
T or F
Secretion is a transport processes similar to
tubular reabsorption but in reverse direction
T
What is secretion important for?
– Disposing of substances not in
filtrate such as drugs (penicillin)
– Eliminating undesirable substances
that have been reabsorbed by
passive processes such as urea
– Ridding body of excessive K+
– Controlling blood pH
T or F
For each substance in plasma, a particular combination of
filtration, reabsorption & secretion occurs.
T
For each of the following name a substance or type of substance that undergoes the described pattern through the nephron
A - Not filtered
B - Filtered but not
reabsorbed or secreted
C - Filtered,
completely reabsorbed & not secreted.
D - Filtered, some
reabsorbed, not secreted
A - Large proteins
B - inulin, creatinine
C - glucose
D - many electrolytes
What 3 layers make up the Glomerular Filtration Barrier?
- Endothelium of glomerular capillaries
- Basement membrane (negatively charged)
- Podocytes of glomerular capsule Glomerular capsule = Bowman’s capsule
Why are Glomerular capillaries more
efficient filters than other
capillaries?
– very large fenestrations
– high hydrostatic pressures driving
filtration (55 vs 18 mmHg)
Why are most proteins unfiltered by the glomerulus?
Most proteins prevented due to negative charge they carry
What is the most abundant protein in the plasma?
albumin
… in urine indicates an
underlying renal disease.
Protein
What force drives glomerular filtration?
glomerular capillary pressure
What 2 forces oppose glomerular filtration?
- Pressure in glomerular/Bowman’s capsule
- Osmotic force due to proteins in plasma
plasma osmotic pressure
T or F
Hydrostatic pressure from the heart favors filtration
T
T or F
An increase in GFR leads an increase in
flow rate and vice versa
T
reabsorption of H2O & other substances
from filtrate partly dependent on rate of
… through tubules
flow
Why does GFR need to be relatively constant?
Increased GFR→inadequate reabsorption → substances lost in urine
Decreased GFR→ reabsorption increased→wastes not excreted
10% increase in GFR equals …L more filtrate to be processed
18
Increased arterial pressure will have what effects on glomerular capillary pressure and GFR?
increases glomerular capillary pressure and GFR
Increased Afferent Arteriolar Resistance will have what effects on glomerular capillary pressure and GFR?
decreased glomerular capillary pressure and GFR
Decreased Afferent Arteriolar Resistance will have what effects on glomerular capillary pressure and GFR?
increases glomerular capillary pressure and GFR
Increased Efferent Arteriolar Resistance will have what effects on glomerular capillary pressure and GFR?
increases glomerular capillary pressure and GFR
Decreased Efferent Arteriolar Resistance will have what effects on glomerular capillary pressure and GFR?
decreased glomerular capillary pressure and GFR
T or F
many daily activities change mean arterial pressure
T
Autoregulation of GFR avoids imbalances in …, … and … excretion
due to changes in mean arterial pressure
fluid, electrolyte and waste
Autoregulation of GFR prevents damage to the filtration barriers by
….
high blood pressures
What are the 2 types of renal autoregulation?
- Myogenic mechanism
- Tubuloglomerular feedback mechanism
Renal autoregulation maintains nearly a constant GFR when MAP is in range of … to … mm Hg - Autoregulation ceases if out of that range
80–180
Controlled regulation of GFR usually involves changes in ….
glomerular capillary pressure
T or F
An increase in glomerular capillary pressure would increase GFR (assuming no other alterations) if there was no autoregulation.
T
Myogenic tone is a property of …. muscle; it involves contraction of the muscle in response to …
arteriolar smooth
stretch
An increase in MAP will … the diameter of the afferent arteriole
reduce
Increase in blood pressure = … =
… = No change in GFR
Myogenic response: Reduction in afferent arteriolar diameter
keeps glomerular capillary pressure constant
What 3 cell populations are seen in the Juxtaglomerular Complex?
1- Macula densa
2- Granular cells (juxtaglomerular, or JG cells)
3- Extraglomerular mesangial cells
The … cells of the juxtaglomerular complex contain chemoreceptors that sense NaCl content of filtrate
Macula densa
The … cells of the juxtaglomerular complex are tall, closely packed cells of ascending limb
Macula densa
Enlarged, smooth muscle cells of arteriole are called …
Granular cells (juxtaglomerular, or JG cells)
The … cells of the juxtaglomerular complex act as mechanoreceptors to sense blood pressure in afferent
arteriole
Granular cells (juxtaglomerular, or JG cells)
The … cells of the juxtaglomerular complex contain secretory granules that contain enzyme renin
Granular (juxtaglomerular, or JG cells)
The … cells of the juxtaglomerular complex are located between arteriole and tubule cells
Extraglomerular mesangial cells
The … cells of the juxtaglomerular complex are interconnected with gap junctions
Extraglomerular mesangial cells
The … cells of the juxtaglomerular complex may pass signals between macula densa and
granular cells
Extraglomerular mesangial cells
The macula densa is a collection of specialized … cells in the …. that detect … concentration of
the fluid in the tubule
epithelial
distal convoluted
tubule
sodium chloride
increase in GFR = increase … reaching
macula densa cells = macula densa sends a
signal to … arteriole to … = reduce GFR = reduce … reaching macula densa
NaCl
afferent
constrict
NaCl
Aldosterone promotes … reabsorption
sodium
Name the three pathways to renin release by granular cells
- Direct stimulation of granular cells by sympathetic
nervous system - Stimulation by activated macula densa cells when
filtrate NaCl concentration is low - Reduced stretch of granular cells
What is the kidneys main mechanism for increasing blood pressure?
Renin-angiotensin-aldosterone mechanism
The chronic overactivation
of the renin angiotensin system
leads to … and …
kidney fibrosis and kidney
disease.
What are the actions of ANG II within the RAAS
- potent vasoconstrictor
- activates sodium reabsorption
- stimulates aldosterone production
- Stimulates ADH release
Direct stimulation of … by the … nervous system increases
renin release
granular cells
sympathetic
What effects does Angiotensinogen II have on the body?
Vasoconstriction
Aldosterone secretion
Increased tubular Na+ reabsorption
Stimulates ADH secretion
thirst
… renin release in turn … the formation of angiotensin II
Increase
increases
T or F
Indirect stimulation of granular cells by the sympathetic nervous system increases
renin release
F
Direct
What are forces that oppose glomerular filtration?
- Pressure in glomerular capsule
- Osmotic force due to proteins in plasma (plasma osmotic pressure)
